Second Mesa, Arizona Weather Forecast Discussion

943
FXUS65 KFGZ 202305
AFDFGZ
Area Forecast Discussion
National Weather Service Flagstaff AZ
405 PM MST Sat Sep 20 2025
.SYNOPSIS...Isolated showers and thunderstorms continue through
Sunday afternoon, with increasing coverage from Sunday night
through Monday. Another low pressure system forming near San Diego
will continue shower and thunderstorm chances at times over
northern Arizona through next week.
&&
.DISCUSSION...Northern Arizona is under a shortwave ridge this
afternoon, with sufficient boundary layer moisture remaining over
Yavapai and southern Coconino County. Despite a capping inversion
near 15k ft msl and very dry air above the inversion (as seen on
the 18Z sounding here in Bellemont), isolated thunderstorms have
developed in the Flagstaff region and parts of the Verde Valley
into southwest Yavapai. Storms have been moving slowly eastward,
and while not particularly strong, very isolated pockets of heavy
rain have fallen including between Cottonwood and Cherry and just
north of Ash Fork. Expect this activity to diminish by sunset or
shortly thereafter.
Sunday and Monday - an upper low diving off the coast of southern
California will pull a plume of much deeper moisture northeastward
into Arizona. Isolated to scattered showers and thunderstorms are
expected to develop by mid to late afternoon from the Mogollon Rim
into Yavapai County. Coverage of showers and storms is forecast to
increase Sunday evening and overnight over much of the area, then
shift to mainly areas along/east of US89/I-17 by Monday afternoon.
With the deeper moisture in place, some pockets of heavy rainfall
could occur despite storm motions of 15-20 kts toward the east,
due to training cells. WPC has placed much of our region except
far northern Arizona under a marginal risk for flash flooding
later Sunday into Monday.
Tuesday through Friday - the cutoff low off the California coast
is shown to slowly move east-northeast onshore and somewhere into
the southwest US. There is plenty of variability in the track of
the low which will impact moisture availability and impacts for
our region. At this point, we are carrying low PoPs (10-30%) each
day, but should some of the farther south solutions verify these
will be raised significantly and heavy rain would be a possibility
- so please stay tuned. This looks most likely later in the week
sometime Thursday or Friday.
&&
.AVIATION...Sunday 21/00Z through Monday 22/00Z...VFR conditions
expected, isolated -SHRA/-TSRA will be ending by 03Z. Fair skies
overnight, with isolated to scattered -SHRA/-TSRA returning after
18-20Z, mainly west of the Interstate 17 corridor. Winds light and
variable or terrain driven overnight, becoming SW 10-15kts gusts
to 20kts after 18Z.
OUTLOOK...Monday 22/00Z through Wednesday 24/00Z...Mainly VFR
conditions, but MVFR possible in heavier SHRA/TSRA. Scattered
showers overnight Sunday into Monday morning with another round of
isolated SHRA/TSRA Monday afternoon into Monday evening. Isolated
-SHRA/-TSRA over the higher terrain Tuesday afternoon. Winds light
 through the extended.
&&
.FIRE WEATHER...Sunday and Monday...Expect shower and thunderstorm
activity to slowly increase Sunday, becoming more widespread Sunday
night and Monday. Daytime winds will be southwest through west at 5
to 15 mph.
Tuesday through Thursday...A chance of showers and thunderstorms
will persist through the period as a low pressure system remains
nearly stationary off the southern California coast. Winds will be
light, generally less than 10 to 15 mph.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
PUBLIC...JJ
AVIATION...Bernhart
FIRE WEATHER...Peterson
For Northern Arizona weather information visit
weather.gov/flagstaff

NWS FGZ Office Area Forecast Discussion